Haha he sure is. My boy gets crazy hyper and then crashes when he has had to take some. The only thing to really worry about is his breathing. As long as there isn't a change he should be fine with the Benadryl. Try switching to the grain free variety. Of kibbles too. That might help and is better overall. Grains aren't needed for dogs to survive. They are just filler as don't have good nutritional value as food without grains.
"There are two temptations to which people fall prey with dogs. The first is to think that biology counts for everything. The second is to think it counts for nothing"
- Tom Junod
“When you KNOW better you DO better.”
― Maya Angelou